Digital camera device and method for producing the same

ABSTRACT

The invention relates to a digital camera device for identifying an object, and to a method and a computer program for producing the same. According to prior art, digital camera devices comprising an objective, a light sensor and an image producing device are known. It is also known that the recorded images have a distortion effect that depends on the focal length of the objective, said distortion effect until now being corrected by calculation in the image producing device during processing of the image. The claim of the invention is to render one such calculated correction superfluous. Towards this end, the density of pixel elements is determined according to the focal length of the objective for the flat arrangement of said pixel elements in the light sensor device.

The invention concerns a digital camera device as well as a method and acomputer program for its production.

Digital camera devices are known in the art for recording an objectwhich may be located in the environment of a vehicle. These types ofcamera devices usually include a lens device for the acceptance andfurther passage of light representing the object. These devices alsohave a light sensor device comprising a plurality of pixel elementsdistributed in flat orientation, with the pixel elements being evenlydistributed within the flat area, e.g. their density is constantthroughout the area of the light sensor device. Each pixel elementproduces a signal which represents the intensity of the light passedfrom the lens device onto the corresponding pixel element. The cameradevice also includes an imaging device for the production of an imagesignal from the plurality of pixel signals, which represents therecorded object.

When a camera device of this type is utilized for the examination of theenvironment of the vehicle it is usually configured in such a way as toimage as wide a field of view as possible. This wide field of view isusually realized by configuring the lens device with a very short focallength. The short focal length, however, has the disadvantage ofassociated distortion effects (so-called fish-eye effect). Thedistortions in the image of a recorded object caused by these effectincrease with decreasing focal length.

These distortion effects are conventionally corrected by software in theimaging device of the digital camera device.

Departing from this prior art, it is the purpose of the presentinvention to further improve a conventional camera device and a methodas well as a computer program for its production in such a fashion thatcorrection of the distortion effects is at least substantially avoided.

This purpose is achieved with the camera device in accordance with claim1. The object the invention is achieved for the above described cameradevice in that the density of the pixel elements in the flat arrangementof the light sensor device is determined in dependence on the focallength of the lens device.

“Density of pixel elements” within the sense of the current inventionrefers to the number of pixel elements per unit area.

ADVANTAGES OF THE INVENTION

The proposed determination of the density of the pixel elements in theflat disposition of the sensor device advantageously permits correctionof the distortion of imaging information caused by the lens device. Thishardware correction obviates the need for software corrections(calculated corrections) in the imaging device during image processing.

Advantageously, not only the density but also its distribution in theflat configuration is optimized to correct for the distortions. Towardsthis end not only the focal length but also the geometric shape andindex of refraction of the lens device are advantageously taken intoconsideration.

The claimed digital camera device is advantageously at least partiallyconfigured as a complementary symmetry metal oxide semi-conductor CMOSor as a charged couple device CCD imaging chip.

The above mentioned purpose of the invention is also achieved by amethod and by a computer program for the production of a digital cameradevice and, in particular, a light sensor device.

In carrying out that method, regions of the flat light sensor devicehaving highest pixel density are advantageously initially calculated andproduced and regions having lower pixel density are subsequentlycalculated and produced. This simplifies production of the chips.

The method and the computer program also share the advantages mentionedabove with respect to the digital camera device.

DRAWINGS

FIG. 1 shows the structure of a digital camera device;

FIG. 2 is a first embodiment of a configuration of the light sensordevice in accordance with the invention; and

FIG. 3 is a second embodiment of a configuration of the light sensordevice in accordance with the invention.

The invention as described in detail below using two embodiments withreference to the accompanying drawings.

FIG. 1 shows the basic construction of a digital camera device 100. Thecamera device 100 serves to recognize an object 200, in particular inthe environment of the vehicle. Towards this end, the device comprises alens device 110 for the acceptance and further passage of lightrepresenting the object 200. The lens device 110 is, in the simplestcase, a single lens. Light passed through the lens device 110 isincident on a light sensor device 120 comprising a plurality of pixelelements 122-1 . . . -N, disposed in flat arrangement. When activated,each of these pixel elements, produces a pixel signal which representsthe intensity of the light incident on the corresponding pixel element.The pixel signals are received by an imaging device 130 disposeddownstream of the light sensor 120 and processed to produce an imagesignal from a plurality of pixel signals which represents the recordedobject 200. The imaging signal is preferentially stored in a storagedevice 140 associated with the camera device 100.

In accordance with the invention, the light sensor device 120 isconfigured in such a fashion that the density of its pixel elements isdetermined in dependence on the focal length of the lens device 110. Inparticular, the density of the pixel elements is lower for smaller focallengths than for larger focal lengths, and vice versa.

In addition to the focal length, the geometrical shape of the lensdevice or its index of refraction should also be taken intoconsideration when optimizing the distribution of the density of pixelelements throughout the flat surface.

FIG. 2 shows a first embodiment for configuration of the light sensordevice 120 in accordance with the invention and, in particular, itspixel distribution. The device has a convex lens device 110 by means ofwhich the light rays passed on to the pixel elements 120-1 . . . -Ndiverge. In a lens device of this type 110, distortion effects occur asthe image is expanded. In accordance with the invention, the separationbetween neighboring pixel elements 120-1 . . . -N is increased incorrespondence with the expansion, e.g. the density of pixel elements isaccordingly reduced.

FIG. 3 shows a second embodiment for the light sensor device 120 inaccordance with the invention. In the event that the lens device 110 isconcave the light ray incident on the pixel elements 122-1 . . . -Nconverges. Distortion effects are thereby produced as the image of theobject 200 on the pixel elements is compressed. In this case, theseparation between the pixel elements 122-1- . . . -N is reduced incorrespondence with the compression, e.g. the density of the pixelelements is increased accordingly.

1-7. (canceled)
 8. A digital camera device for detecting an object, inparticular in the environment of a vehicle, the device comprising: alens member for the acceptance and further passage of light representingthe object; a light sensor member having a plurality of pixel elementsdisposed in flat arrangement, wherein each pixel element produces apixel signal which represents an intensity of light transported fromsaid lens member onto that pixel element, wherein a density of saidpixel elements within said light sensor member is distributed independence on a geometric shape or an index of refraction of said lensmember; and an imaging member for production of an image signal from aplurality of pixel signals representing a recorded object.
 9. Thedigital camera device of claim 8, wherein said density of pixel elementsis defined in dependence on a focal length of said lens member.
 10. Thedigital camera device of claim 8, wherein said camera device is at leastpartially configured as a CMOS or CD imaging chip.
 11. A method forproduction of a digital camera device having a lens member and a lightsensor member disposed downstream of the lens member and having aplurality of pixel elements in flat arrangement, the method comprisingthe following steps: a) determining a density distribution of the pixelelements in dependence on a geometric shape or an index of refraction ofthe lens member; b) initially manufacturing pixels in a region of highpixel density; and c) subsequently producing regions having lower pixeldensity.
 12. The method of claim 11, wherein the density distribution ofthe pixel elements is defined by a focal length of the lens member. 13.A computer program having a program code configured to calculate thedistribution of the density of pixel elements for the light sensormember according to the method of 11.